<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<input type="text" name="" id="username" value="" />
		<h1></h1>
		<script type="text/javascript">
			let inputDom = document.querySelector("#username")
			inputDom.oninput = function(){
				document.querySelector("h1").innerHTML = inputDom.value
			}
		</script>
	</body>
</html>
